Gone quicker than a 24-pack of TP... Remember that $349B in forgivable loans to small businesses from the $2T stimulus package? That ran out quickly — especially since not-so-small businesses got multi-million loans. Now Congress has approved an extra $321B for Paycheck Protection Program loans (PPP), which become "free money" for businesses if they keep their workers employed. All that free money though is adding up...
The US borrows $$$ by offering IOUs to investors... They're called "Treasury securities", aka US government bonds. Most of that debt is held by regular Americans through pension and mutual funds and a large part is owned by foreign governments (think China).
There are 2 ways to pay down national debt... and they both have consequences.